Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. KalleH

    screw relaxation

    I was probably the one who posted the link to the Volvo standards. However, 5.3 is just about torque/tension relationships.
  2. KalleH

    screw relaxation

    That is easy to say if you are not in the heavy vehicle business, where this is standard on chassis, to which brackets are bolted.
  3. KalleH

    Fastener Torque vs Clamping Force

    Volvo corporate standard 5511,21, which can be found on the following adress has excellent tables to determine clamping force / torque relationships depending on thread and base friction. Please, see the adress below: http://www.tech.volvo.se/standard/eng/
  4. KalleH

    screw relaxation

    Does anyone have a reference for the relaxation of screw joints in micrometer as function of aspects such as surface roughness and paint type and paint thickness? Thanks!
  5. KalleH

    change in accelerance

    Assume that I have a board like structure lying down and suspended in its four corners. I have measured or calculated the accelerance (a/F) between a point A of the board and the base. I now introduce four isolators between the base and the four corners of the board. My question: Is there an...
  6. KalleH

    Need to check my Rainflow analysis subroutine

    Samer, I have constructed the following subroutine, which I have checked using handbook methods and LMS tekware. (I will however not guarantee its accuracy.) Public Sub FromToRainFlow() 'Counts cycles according to the rain flow algorithm. 'Precondition: dPeaks[] 'Postcondition: dFromToRain[]...
  7. KalleH

    My parasitic harmonics are moving

    Never mind. In the case of the flextest system, I acquired the signals through the auxiliary channels. Apparently, these are not low pass filtered to prevent aliasing. Hence, my conclusion is that the frequencies around 80Hz are simply the ones around 500Hz aliased. Sorry! /Karl
  8. KalleH

    My parasitic harmonics are moving

    When using a 3DOF servohydraulic shaker, I have lately encountered some odd harmonics in my 3DOF response signal. The frequency content of the non-stationary noise that I try to simulate is 5-35 Hz. When measuring using a MTS flextest system, the parasitic harmonics end up at around 80Hz. All...
  9. KalleH

    Nastran batch

    Thomas, Thank you for providing the command for calling on the batchfile. It is actually a friend of mine who asked me this question for a joint project, so I won't be able to get to much into the details. However, what he wants to do is to write the actual batch file. I.e. he would like to...
  10. KalleH

    Nastran batch

    Hi everyone! Does anyone have a web reference to a guide for writing batch files for solving in Nastran? Cheers!
  11. KalleH

    [THERM-STRUC] TEMPERATURE MAPPING

    10031978, Not really. I have myself never had to write one with this purpose. However, the APDL programmer's guide in the Ansys documentation quickly gives you all the information you need to write this kind of an APDL loop. A word of caution: APDL will work well for small models like yours...
  12. KalleH

    [THERM-STRUC] TEMPERATURE MAPPING

    To me, the most straightforward approach, seems to be to make a small APDL loop that determines and applies the right nodal temperatures. This based on interpolation from the eight nodal temperatures that you have. Cheers!
  13. KalleH

    Simulating thrre directional vibration on a one-directional shaker

    CaptainCrunch, I guess that the simplest way for you to determine if your doing things right would be to intrument a specimen with strain gauges in the most critical points and obtain both strain and acceleration when you do your DAQ in the field. Then see if the same points will see the same...
  14. KalleH

    Vibration Fatigue

    I agree with Dampit. Dirlik-Bishops method is the most appropriate one for non-narrow bandwidth noise that can be characterized as stationary random. It will give you a nice range-no mean histogram, which you can use to calculate damage. HalfPenny @ nCode has written a nice indroduction to the...
  15. KalleH

    aliasing after non-linear FEA

    Tom, I guess the approach you describe is the way to go for a linear system, where I can use mode superposition. However, in this case I have non-linear springs, and hence the modes at lower amplitude will not give me all the information I need for the analysis. Hence I solve the problem in...
  16. KalleH

    aliasing after non-linear FEA

    I am performing a transient FEA on a non-linear system. The loading signal has been filtered properly and has no aliasing. However, as the system is non linear, the output signal will have a wider frequency content. How do I know if aliasing has occurred or not? I assume that the key somehow...
  17. KalleH

    Random Analysis with MDOF load

    When I try to perform a random vibration analysis with MDOF load and the correlation between the loading DOF:s described through COVAL and QDVAL, the results spectra are erroneous. The amplitude of the PSD spectra obtained in post26 become partly negative. Ansys claims that this is an error...

Part and Inventory Search

Back
Top